Starter / Alternator Question.

[Young Ned]

Got a bit of a headscratcher on a Mk5 (H) Astra CDTi, and would be really grateful of a bit of help!

After running through some standing water a couple of weeks back, the car wouldnt restart the first time but gradually got better, I assume when dried out. After getting a couple of flat batteries since, I noted the voltage when running to be down at around 12.5V. To keep myself on the road I kept a charged battery in the boot for any Jump starting requirements, but now all I get when trying to start is the starter solenoid clicking (even with a freshly charged battery.

Through a bit of tracing and checking, I have noticed the starter motor is down to earth on the small connection of the smaller, upper cylinder of the starter (Im guessing this is the solenoid??)Is this an indication the starter is dead? And am I correct in thinking this connection is the switched live, and the large one next to it the permanant live? The smaller connection (torx type) was tested with the cable disconnected, the tab was down to earth at 0 ohms and the cable was open circuit to earth.

The other question is, would the (possible) failed starter be able to drag down the charge of the alternator when its running? or would it appear I have managed to ruin two expensive round shiny compenents?!

This car was my first attempt at getting a newer car that would be a reliable runaround and as you can see it is going well so far Thanks in advance!!

[CoolHands]

if voltage when running was 12.5v, then your alternator is not giving out enough juics assuming all fuses and connections are clean, tight, and not melted / corroded).

My money is on new alternator, fit, then retest.

[TonyRPH]

If testing the starter motor with an ohm meter, I would expect very low resistance readings.

If it was short circuit, you would have some slightly different symptoms, e.g. all dashboard lights would go off completely when the key is turned, as the battery + would effectively be shorted to earth.

Either you have a faulty solenoid, or the battery voltage is simply too low to turn the motor over.

With the engine idling, the voltage across the battery should be around 13.8v or so, if the alternator was working correctly.

[Young Ned]

Thanks, Its really puzzling me. Just tested out the same small cable to the starter on my mates car which is the same model and got the same result. Lucky as I was going to order a new starter tomorrow. I am confused though as the car wont even jump start off another car, or charged battery. It does look as though it shorts completely when actually trying to turn it over as the dash display all blacks out. Nightmare!!

[buggalugs]

This could be bks but isn't it a switched earth?

You alternator isn't charging and all the symptoms now are of a flat battery, could you have made a mistake when trying a charged one to make you think that that's not it?

[Young Ned]

I hope so! But have tried jump starting from another car with the terminals on my car disconnected from the battery and still nothing.

[markiemark]

If you get a click from the starter try hitting it a few times, might be sticking.

[Young Ned]

Thanks all, Totally at a loss to why it worked the second time but managed to get the car going with the battery off of my Renault 5 of all things. Alternator is showing around 13 on the onboard computer but I am measuring 13.8 across the terminals. Voltage drops quite badly to around 12 or so when the fan is on high or with the lights on so I'm guessing the alternator/voltage regulator needs replacing before winter!

Battery is the original Varta/GM Item (car is 07 plate) so I guess its at the end of its life. One thing that I did notice though is that the original battery has an indicator lamp type thingy, but only indicates when the battery is tilted!! From what I can tell it appears the fluid tips into this thing and makes it glow. Can anybody explain this to me!!

Thanks for the help. Appears I was chasing my tail anyway! But now have a running car